In recent years, the number of instruments and functions provided in vehicles has increased. When driving the vehicle, the driver needs to process various kinds of information acquired from the inside and outside of the vehicle.
Various kinds of information processed by the driver include, for example, information on the speed of the vehicle, the number of revolutions of the engine, a radio channel number displayed on a center console, information on a music track number, information on the map which is displayed on the screen of a car navigation system or route guidance, and information for supporting driving safety, such as information for warning the driver against danger around the vehicle.
In general, the driver visually acquires information displayed on an instrument panel or a center console panel. However, when there is a large difference between the direction of the driver's eye and the direction in which information is displayed or when the distance between the driver and the display position of the information is large, the driver must move the line of sight or adjusts a focus in order to check the content of the information.
In order to significantly reduce the amount of movement of the direction of the driver's eye or the amount of adjustment of the focus, a head-up display (HUD) has been developed. The HUD is a display that displays predetermined information in a specific range from the upper part of the dash board of the vehicle to the windshield.
For example, there are two types of HUDs, that is, a type in which the driver directly views a display apparatus, such as a liquid crystal display or an OELD (Organic Electroluminescent Display) and another type that projects light emitted from a liquid crystal display, an OELD, or a display apparatus including a laser light source onto the windshield.
The use of the HUD makes it possible to reduce the time required for the driver to move the eye in order to view the display when the driver drives the vehicle while viewing the front, as compared to the case in which the driver views the instrument panel or the center console.
The type of HUD in which light is projected onto the windshield is characterized in that display information overlaps the foreground of the vehicle and can reduce the optical path length between the driver and the display apparatus. In this way, the driver can view the display information with little time to adjust the focus.
The use of the HUD makes it possible to display information at a position close to the center of the field of view of the driver and it is expected that the recognition of display information by the driver will be greatly improved. It is considered that the HUD is particularly effective for an aged person with a low visual function.
When information is displayed at the position close to the center of the field of view of the driver, the driver is likely to feel discomfort. Therefore, an information display method that enables the driver to easily recognize information and also prevent the driver from feeling discomfort is needed. A technique has been proposed which displays information in the vicinity of the field of view of the driver (operator) and adds a visual attraction to the display information at a given timing, thereby improving the recognition of the display information (for example, see Non-patent Literature 1).
For example, in Non-patent Literature 1, a motion effect, such as longitudinal vibration or lateral vibration, is added to the display information, thereby obtaining the effect of enabling the driver to easily recognize the display information and preventing the driver from feeling discomfort as the visual attraction. In addition, as an example in which the visual attraction using the vibration is applied during the traveling of the vehicle, Patent Literature 1 discloses a method of improving the recognition of information by the driver using lateral vibration.
Patent Literature 1 discloses a display apparatus and method for a vehicle in which the flow of light with a move speed that is operatively associated with the traveling of the vehicle is generated in the field of view of the driver and a non-display region indicating the existence of another vehicle is provided on the flow. In addition, in Patent Literature 1, when the non-display region is maintained for a predetermined period of time, the non-display region is vibrated in the horizontal direction in order to prevent the driver from being accustomed to the non-display region.
When the HUD is used to display a predetermined image on the windshield so as to be vibrated, the image overlaps the foreground of the vehicle that is changed over time. Therefore, when the display method disclosed in Patent Literature 1 is used, it is possible to display an image such that the driver can easily recognize the displayed image without discomfort.
Specifically, for example, the visual attraction of lateral vibration is added to the image indicating that there is, for example, a pedestrian (attention object) on the path of the vehicle and then the image is displayed on the HUD. In this way, it is possible to reliably notify the driver of the existence of the attention object in a short time.